Redirect /:id to canonical URL for post. (#617)
* Redirect /:id to canonical URL for post. This implements redirection of `/:id` (a short-form URL to a post) to the post's canonical URL. Libreddit issues a `HEAD /:id` to Reddit to get the canonical URL, and on success will send an HTTP 302 to a client with the canonical URL set in as the value of the `Location:` header. This also implements support for short IDs for non-ASCII posts, c/o spikecodes. Co-authored-by: spikecodes <19519553+spikecodes@users.noreply.github.com>
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Daniel Valentine
GitHub
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commit
c6487799ed
3 changed files with 152 additions and 66 deletions
182
src/client.rs
182
src/client.rs
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@ -1,13 +1,59 @@
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use cached::proc_macro::cached;
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use futures_lite::{future::Boxed, FutureExt};
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use hyper::{body, body::Buf, client, header, Body, Request, Response, Uri};
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use hyper::{body, body::Buf, client, header, Body, Method, Request, Response, Uri};
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use libflate::gzip;
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use percent_encoding::{percent_encode, CONTROLS};
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use serde_json::Value;
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use std::{io, result::Result};
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use crate::dbg_msg;
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use crate::server::RequestExt;
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const REDDIT_URL_BASE: &str = "https://www.reddit.com";
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/// Gets the canonical path for a resource on Reddit. This is accomplished by
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/// making a `HEAD` request to Reddit at the path given in `path`.
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///
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/// This function returns `Ok(Some(path))`, where `path`'s value is identical
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/// to that of the value of the argument `path`, if Reddit responds to our
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/// `HEAD` request with a 2xx-family HTTP code. It will also return an
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/// `Ok(Some(String))` if Reddit responds to our `HEAD` request with a
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/// `Location` header in the response, and the HTTP code is in the 3xx-family;
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/// the `String` will contain the path as reported in `Location`. The return
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/// value is `Ok(None)` if Reddit responded with a 3xx, but did not provide a
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/// `Location` header. An `Err(String)` is returned if Reddit responds with a
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/// 429, or if we were unable to decode the value in the `Location` header.
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#[cached(size = 1024, time = 600, result = true)]
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pub async fn canonical_path(path: String) -> Result<Option<String>, String> {
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let res = reddit_head(path.clone(), true).await?;
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if res.status() == 429 {
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return Err("Too many requests.".to_string());
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};
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// If Reddit responds with a 2xx, then the path is already canonical.
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if res.status().to_string().starts_with('2') {
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return Ok(Some(path));
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}
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// If Reddit responds with anything other than 3xx (except for the 2xx as
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// above), return a None.
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if !res.status().to_string().starts_with('3') {
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return Ok(None);
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}
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Ok(
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res
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.headers()
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.get(header::LOCATION)
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.map(|val| percent_encode(val.as_bytes(), CONTROLS)
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.to_string()
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.trim_start_matches(REDDIT_URL_BASE)
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.to_string()
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),
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)
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}
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pub async fn proxy(req: Request<Body>, format: &str) -> Result<Response<Body>, String> {
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let mut url = format!("{}?{}", format, req.uri().query().unwrap_or_default());
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@ -63,21 +109,39 @@ async fn stream(url: &str, req: &Request<Body>) -> Result<Response<Body>, String
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.map_err(|e| e.to_string())
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}
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fn request(url: String, quarantine: bool) -> Boxed<Result<Response<Body>, String>> {
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/// Makes a GET request to Reddit at `path`. By default, this will honor HTTP
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/// 3xx codes Reddit returns and will automatically redirect.
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fn reddit_get(path: String, quarantine: bool) -> Boxed<Result<Response<Body>, String>> {
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request(&Method::GET, path, true, quarantine)
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}
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/// Makes a HEAD request to Reddit at `path`. This will not follow redirects.
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fn reddit_head(path: String, quarantine: bool) -> Boxed<Result<Response<Body>, String>> {
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request(&Method::HEAD, path, false, quarantine)
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}
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/// Makes a request to Reddit. If `redirect` is `true`, request_with_redirect
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/// will recurse on the URL that Reddit provides in the Location HTTP header
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/// in its response.
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fn request(method: &'static Method, path: String, redirect: bool, quarantine: bool) -> Boxed<Result<Response<Body>, String>> {
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// Build Reddit URL from path.
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let url = format!("{}{}", REDDIT_URL_BASE, path);
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// Prepare the HTTPS connector.
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let https = hyper_rustls::HttpsConnectorBuilder::new().with_native_roots().https_or_http().enable_http1().build();
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// Construct the hyper client from the HTTPS connector.
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let client: client::Client<_, hyper::Body> = client::Client::builder().build(https);
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// Build request
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// Build request to Reddit. When making a GET, request gzip compression.
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// (Reddit doesn't do brotli yet.)
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let builder = Request::builder()
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.method("GET")
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.method(method)
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.uri(&url)
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.header("User-Agent", format!("web:libreddit:{}", env!("CARGO_PKG_VERSION")))
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.header("Host", "www.reddit.com")
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.header("Accept", "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8")
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.header("Accept-Encoding", "gzip") // Reddit doesn't do brotli yet.
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.header("Accept-Encoding", if method == Method::GET { "gzip" } else { "identity" })
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.header("Accept-Language", "en-US,en;q=0.5")
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.header("Connection", "keep-alive")
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.header("Cookie", if quarantine { "_options=%7B%22pref_quarantine_optin%22%3A%20true%7D" } else { "" })
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@ -87,8 +151,15 @@ fn request(url: String, quarantine: bool) -> Boxed<Result<Response<Body>, String
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match builder {
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Ok(req) => match client.request(req).await {
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Ok(mut response) => {
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// Reddit may respond with a 3xx. Decide whether or not to
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// redirect based on caller params.
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if response.status().to_string().starts_with('3') {
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request(
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if !redirect {
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return Ok(response);
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};
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return request(
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method,
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response
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.headers()
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.get("Location")
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@ -98,56 +169,64 @@ fn request(url: String, quarantine: bool) -> Boxed<Result<Response<Body>, String
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})
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.unwrap_or_default()
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.to_string(),
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true,
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quarantine,
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)
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.await
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} else {
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match response.headers().get(header::CONTENT_ENCODING) {
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// Content not compressed.
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None => Ok(response),
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.await;
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};
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// Content gzipped.
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Some(hdr) => {
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// Since we requested gzipped content, we expect
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// to get back gzipped content. If we get
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// back anything else, that's a problem.
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if hdr.ne("gzip") {
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return Err("Reddit response was encoded with an unsupported compressor".to_string());
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}
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match response.headers().get(header::CONTENT_ENCODING) {
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// Content not compressed.
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None => Ok(response),
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// The body must be something that implements
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// std::io::Read, hence the conversion to
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// bytes::buf::Buf and then transformation into a
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// Reader.
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let mut decompressed: Vec<u8>;
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{
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let mut aggregated_body = match body::aggregate(response.body_mut()).await {
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Ok(b) => b.reader(),
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Err(e) => return Err(e.to_string()),
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};
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let mut decoder = match gzip::Decoder::new(&mut aggregated_body) {
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Ok(decoder) => decoder,
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Err(e) => return Err(e.to_string()),
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};
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decompressed = Vec::<u8>::new();
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match io::copy(&mut decoder, &mut decompressed) {
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Ok(_) => {}
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Err(e) => return Err(e.to_string()),
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};
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}
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response.headers_mut().remove(header::CONTENT_ENCODING);
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response.headers_mut().insert(header::CONTENT_LENGTH, decompressed.len().into());
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*(response.body_mut()) = Body::from(decompressed);
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Ok(response)
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// Content encoded (hopefully with gzip).
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Some(hdr) => {
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match hdr.to_str() {
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Ok(val) => match val {
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"gzip" => {}
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"identity" => return Ok(response),
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_ => return Err("Reddit response was encoded with an unsupported compressor".to_string()),
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},
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Err(_) => return Err("Reddit response was invalid".to_string()),
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}
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// We get here if the body is gzip-compressed.
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// The body must be something that implements
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// std::io::Read, hence the conversion to
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// bytes::buf::Buf and then transformation into a
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// Reader.
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let mut decompressed: Vec<u8>;
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{
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let mut aggregated_body = match body::aggregate(response.body_mut()).await {
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Ok(b) => b.reader(),
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Err(e) => return Err(e.to_string()),
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};
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let mut decoder = match gzip::Decoder::new(&mut aggregated_body) {
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Ok(decoder) => decoder,
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Err(e) => return Err(e.to_string()),
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};
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decompressed = Vec::<u8>::new();
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if let Err(e) = io::copy(&mut decoder, &mut decompressed) {
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return Err(e.to_string());
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};
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}
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response.headers_mut().remove(header::CONTENT_ENCODING);
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response.headers_mut().insert(header::CONTENT_LENGTH, decompressed.len().into());
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*(response.body_mut()) = Body::from(decompressed);
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Ok(response)
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}
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}
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}
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Err(e) => Err(e.to_string()),
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Err(e) => {
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dbg_msg!("{} {}: {}", method, path, e);
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Err(e.to_string())
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}
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},
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Err(_) => Err("Post url contains non-ASCII characters".to_string()),
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}
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@ -158,9 +237,6 @@ fn request(url: String, quarantine: bool) -> Boxed<Result<Response<Body>, String
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// Make a request to a Reddit API and parse the JSON response
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#[cached(size = 100, time = 30, result = true)]
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pub async fn json(path: String, quarantine: bool) -> Result<Value, String> {
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// Build Reddit url from path
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let url = format!("https://www.reddit.com{}", path);
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// Closure to quickly build errors
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let err = |msg: &str, e: String| -> Result<Value, String> {
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// eprintln!("{} - {}: {}", url, msg, e);
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@ -168,7 +244,7 @@ pub async fn json(path: String, quarantine: bool) -> Result<Value, String> {
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};
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// Fetch the url...
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match request(url.clone(), quarantine).await {
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match reddit_get(path.clone(), quarantine).await {
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Ok(response) => {
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let status = response.status();
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@ -186,7 +262,7 @@ pub async fn json(path: String, quarantine: bool) -> Result<Value, String> {
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.as_str()
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.unwrap_or_else(|| {
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json["message"].as_str().unwrap_or_else(|| {
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eprintln!("{} - Error parsing reddit error", url);
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eprintln!("{}{} - Error parsing reddit error", REDDIT_URL_BASE, path);
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"Error parsing reddit error"
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})
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})
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31
src/main.rs
31
src/main.rs
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@ -17,7 +17,7 @@ use futures_lite::FutureExt;
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use hyper::{header::HeaderValue, Body, Request, Response};
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mod client;
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use client::proxy;
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use client::{canonical_path, proxy};
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use server::RequestExt;
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use utils::{error, redirect, ThemeAssets};
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@ -259,9 +259,6 @@ async fn main() {
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app.at("/r/:sub/:sort").get(|r| subreddit::community(r).boxed());
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// Comments handler
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app.at("/comments/:id").get(|r| post::item(r).boxed());
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// Front page
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app.at("/").get(|r| subreddit::community(r).boxed());
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@ -279,13 +276,25 @@ async fn main() {
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// Handle about pages
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app.at("/about").get(|req| error(req, "About pages aren't added yet".to_string()).boxed());
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app.at("/:id").get(|req: Request<Body>| match req.param("id").as_deref() {
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// Sort front page
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Some("best" | "hot" | "new" | "top" | "rising" | "controversial") => subreddit::community(req).boxed(),
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// Short link for post
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Some(id) if id.len() > 4 && id.len() < 7 => post::item(req).boxed(),
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// Error message for unknown pages
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_ => error(req, "Nothing here".to_string()).boxed(),
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app.at("/:id").get(|req: Request<Body>| {
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Box::pin(async move {
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match req.param("id").as_deref() {
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// Sort front page
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Some("best" | "hot" | "new" | "top" | "rising" | "controversial") => subreddit::community(req).await,
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// Short link for post
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Some(id) if (5..7).contains(&id.len()) => match canonical_path(format!("/{}", id)).await {
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Ok(path_opt) => match path_opt {
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Some(path) => Ok(redirect(path)),
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None => error(req, "Post ID is invalid. It may point to a post on a community that has been banned.").await,
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},
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Err(e) => error(req, e).await,
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},
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// Error message for unknown pages
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_ => error(req, "Nothing here".to_string()).await,
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}
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})
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});
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// Default service in case no routes match
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@ -716,10 +716,11 @@ pub fn redirect(path: String) -> Response<Body> {
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.unwrap_or_default()
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}
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pub async fn error(req: Request<Body>, msg: String) -> Result<Response<Body>, String> {
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/// Renders a generic error landing page.
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pub async fn error(req: Request<Body>, msg: impl ToString) -> Result<Response<Body>, String> {
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let url = req.uri().to_string();
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let body = ErrorTemplate {
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msg,
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msg: msg.to_string(),
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prefs: Preferences::new(req),
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url,
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}
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